A tree down at Queanbeyan School where a mother and her child were injured. Photo: Benjamin Doherty

Dr Brown said a small number of outpatients were affected by the flooding and they were being contacted to make alternative arrangements.

Flooded streets were common, with one woman losing her dog after it was washed down an uncovered manhole. Canberra Airport grounded flights intermittently during the storm, at some points delaying all flights in and out of the territory.

The ACT's roads were severely affected by the weather, with flooding and fallen trees blocking traffic and delaying motorists.

There were a number of car accidents across Canberra, including one car which rolled on the Federal Highway and a separate collision between a car and a bus. A woman was also injured in Fyshwick when a branch smashed through her windscreen on Ipswich Street.

Winds reached gale-force speeds of up to 56km/h at 2.39pm, with gusts reaching 74km/h.

One Fyshwick business on Lithgow Street lost half its roof and several other businesses were affected by fallen trees. Tuggeranong had the highest rainfall for the territory, with 75.8 millimetres falling in just 3½ hours.

Canberra's entire rainfall for December, January and February had been just 97 millimetres up until Wednesday, with the recent deluge more than doubling it. It also almost met Canberra's average rainfall for February of 85 millimetres.

Weatherzone meteorologist Brett Dutschke said it was the most intense storm in the territory in at least three years. Conflicting weather patterns around the ACT had made Canberra the eye of a perfect storm. ''We've had very moist, warm air coming down from the north and that's met with a mass of colder, drier air from the south,'' he said. ''[Canberra] was about in the ideal position today for the biggest contrast in air masses.''

The forecast for the days ahead:

Thursday: 10C, 23C. Mostly sunny.

Friday: 6C, 25C. Partly cloudy, the chance of showers.

Saturday: 8C, 27C. Mostly sunny, light winds.

Sunday: 9C, 27C. Mostly sunny.

Residents can reach the ACTSES on 132-500.

Canberrans took to Twitter to share pictures of sheets of water buffeting the city and the dark menacing clouds gathering overhead. Here's a look at some of the best: